The present invention relates to the field of marking gas turbine engine parts.
A field of application of the invention is that of marking aviation turbine engine parts with a predefined graphic having a holographic type effect, in particular to enable them to be identified and authenticated.
In the field of aviation, it is known to apply a serial number (e.g. in the form of a hexadecimal-based code or in the form of a Datamatrix code) to certain parts of an engine for the purpose of identifying such parts (where this is referred to as “marking”). Using such a number, it is possible to be certain about the authenticity of parts and about their origin.
Marking is particularly desired for turbine and compressor blades of an aviation turbine engine. Specifically, blades are critical spare parts for which it is important to be certain of their origin in order to take account of the influence of replacing such parts on the lifetime of the turbine or of the compressor in question.
Parts, and in particular turbine or compressor blades of an aviation turbine engine, may be marked in various ways. Thus, laser marking is known in which the laser performs a plurality of passes, thereby making an imprint in the part for marking by removing material. Mechanical marking is also known in which use is made of a hammer or a pneumatic piston that imparts successive impacts, thereby imprinting a serial number on the part for marking. Also known is marking performed by means of a manual or automatic milling machine.
Marking techniques that rely on the principle of removing material or of deforming the part for marking in order to put a desired graphic thereon present a manifest drawback concerning the health of the material of the part for marking. Particularly when a part is made out of a single-crystal metal alloy, deformation or removal of material can lead to localised recrystallisation or to an irreversible microstructure defect.
Furthermore, when a part is to be marked with a predefined graphic having a holographic type effect, known marking methods rely on adding material, e.g. by modifying a photosensitive film or by superposing images within a polymer.
However, such techniques of marking by adding material are complex and expensive to perform, in particular on a part that is made out of a single-crystal metal alloy.